JP2020133715A - Relief valve - Google Patents

Abstract

To provide a relief valve capable of reducing pressure override even in a case where a flow rate increases.SOLUTION: A relief valve V of the present invention comprises a cylindrical housing 1 having an annular valve seat 2 inside, a valve body 3 movably housed in the housing 1 and seated on and off the annular valve seat 2, and a spring 4 that energizes the valve body 3 toward the annular valve seat 2. The valve body 3 comprises: a sliding contact shaft 3a slidingly contacting the inner circumference of the housing 1; a disc-shaped seating part 3b continuous to the rear end of the sliding contact shaft 3a and seated on and off the annular valve seat 2; a main slit 3c formed from the front end to the rear end of the sliding contact shaft 3a and opened to the lateral of the sliding contact shaft 3a; and a sub flow passage 3d that is opened from the front end side with respect to the rear end of the main slit 3c on the lateral of the sliding contact shaft 3a, and adds a flow passage in a circumferential direction to a flow passage formed by the main slit 3c through the front end of the sliding contact shaft 3a.SELECTED DRAWING: Figure 1

Description

The present invention relates to an improvement of a relief valve.

Conventionally, in this type of relief valve, for example, a tubular shape provided in the middle of a passage connecting two pressure chambers provided inside a hydraulic damper that generates a high damping force and having an annular valve seat inside. The housing, the valve body housed in the housing, the spring seat screwed to the inner circumference of the housing, and the valve body attached between the valve body and the spring seat toward the annular valve seat. It is known that a coil spring is provided (see, for example, Patent Document 1).

The housing has a small diameter portion and a large diameter portion inward, and has an annular valve seat formed by a step portion at the boundary between the small diameter portion and the large diameter portion. The valve body of the relief valve consists of a sliding contact shaft that slides into the inner circumference of the small diameter portion, a disc-shaped seating portion that connects to the rear end of the sliding contact shaft and is detached and seated on the annular valve seat, and a sliding contact shaft. It is provided with a U-shaped main slit that penetrates the sliding contact shaft in the radial direction from the front end to the rear end. When the valve body receives pressure from the spring seat side, the seating portion is seated on the annular valve seat to close the inside of the housing, and conversely, when pressure is received from the sliding contact shaft side, the seating portion is seated on the annular valve seat. The main slit faces the large diameter part, and the inside of the housing is opened to allow the flow of hydraulic oil. Further, the rear end shape of the main slit is a semicircular shape, and the opening amount of the sliding contact shaft with respect to the side increases as the main slit moves from the rear end to the tip.

In the relief valve configured in this way, the flow path area is determined by the area where the main slit faces the large diameter portion in the radial direction, so that the flow path increases as the amount of retreat of the valve body from the annular valve seat increases. The area also increases. Therefore, when the relief valve configured in this way is used as the damping valve of the hydraulic damper, the characteristics of the damping force generated with respect to the piston speed of the hydraulic damper are statically shown by the solid line in FIG. When the piston speed is low, the amount of retreat of the valve body with respect to the annular valve seat is small, so only the rear end of the main slit opens, so the damping coefficient increases, and the piston speed increases and parts other than the rear end of the main slit also When the valve is opened, the flow path area increases significantly with the piston speed, and the damping coefficient becomes low. That is, the relief valve has a characteristic that statically, when the upstream pressure increases, the opening amount of the main slit increases and the pressure override decreases.

Japanese Unexamined Patent Publication No. 2011-163380

The above-mentioned relief valve causes a pressure loss by narrowing the flow of the hydraulic oil when the hydraulic oil passes through the main slit S of the valve body VB, but it is viewed dynamically as shown by the arrow in FIG. The flow of hydraulic oil that has passed through the main slit S collides with the inner peripheral surface of the housing H in the radial direction of the sliding shaft P and is bent at a right angle. Therefore, in addition to the resistance generated when the hydraulic oil throttles the flow of the hydraulic oil by the main slit S, the resistance that hinders the flow of the hydraulic oil is generated.

As the flow rate of the hydraulic oil passing through the relief valve increases, the resistance that obstructs the above-mentioned flow also increases. Therefore, when viewed dynamically, the characteristics of the relief valve are as shown by the broken line in FIG. Pressure override increases in areas where there is more. Therefore, when the conventional relief valve is used for the hydraulic damper, the damping coefficient of the hydraulic damper becomes larger than the damping coefficient aimed at in the high speed range at the piston speed.

That is, although the opening area of the main slit with respect to the amount of retreat of the valve body from the annular valve seat is sufficiently secured, the resistance that hinders the flow of hydraulic oil is superimposed on the resistance given to the flow of hydraulic oil by the main slit. Therefore, when the flow rate increases, the actual pressure loss exceeds the design pressure loss.

Therefore, an object of the present invention is to provide a relief valve capable of reducing pressure override even when the flow rate increases.

In order to solve the above problems, the relief valve of the present invention includes a tubular housing having an annular valve seat inside, a valve body that is movably housed in the housing and is detached and seated on the annular valve seat, and a valve body. The valve body is equipped with a spring that urges the annular valve seat, and the valve body has a sliding contact shaft that slides into the inner circumference of the housing and a disc-shaped valve that connects to the rear end of the sliding contact shaft and takes off and seats on the annular valve seat. A seating portion, a main slit formed from the tip to the rear end of the sliding contact shaft and opening to the side of the sliding contact shaft, and a side of the sliding contact shaft, which is on the tip side of the rear end of the main slit. It is provided with a sub-flow path that opens from the center and leads to the tip of the sliding contact shaft to add a flow path in the circumferential direction to the flow path formed by the main slit.

According to the relief valve configured in this way, as described above, when the valve body retracts from the annular valve seat, the sub-flow path is opened later than the opening of the main slit, and the sub-flow path is the main slit. A flow path can be added to the flow path in the circumferential direction of the sliding contact axis to disperse the liquid flow in the sub-flow path.
Further, the main slit in the relief valve is formed so as to penetrate the sliding contact shaft in the radial direction, and the sub flow path disperses the flow rate of the main slit and the sliding contact shaft when the seating portion retracts from the annular valve seat and opens. The flow of the liquid may be diffused in the circumferential direction of the. According to the relief valve configured in this way, the sub-flow path increases the area of the liquid outlet to facilitate the diffusion of the liquid flow, and the flow rate distribution passing between the housing and the seating portion of the valve body is distributed. Since it is dispersed in the circumferential direction, the resistance due to the liquid flow being bent by the housing is reduced, and the pressure override can be further reduced.

Further, the main slit penetrates the sliding contact shaft in the radial direction and is formed from the tip end to the rear end of the sliding contact shaft, and the sub flow path opens from the side of the sliding contact shaft to the side of the sliding contact shaft of the main slit. It may be formed so as to communicate with a lateral opening that opens toward the side. According to the relief valve configured in this way, since the sub flow path is directly communicated with the side opening of the main slit, the liquid that has passed through the narrow main slit flows in the circumferential direction as the sub flow path opens. It can penetrate into a wide sub-channel and efficiently diffuse the liquid flow in the circumferential direction of the sliding contact shaft to effectively reduce pressure override.

The sub-flow path may be formed by providing a horizontal hole communicating with the main slit in the sliding contact shaft, or the main slit may penetrate the sliding contact shaft in the radial direction and be directed from the tip end to the rear end of the slide contact shaft. It may be formed in a direction orthogonal to the relative. Even if the sub-flow path is formed in this way, when the valve body retracts from the annular valve seat and the sub-flow path is opened, the flow path of the sub-flow path is added to the flow path of the main slit to allow the liquid flow. It can be dispersed and pressure override can be reduced.

According to the relief valve of the present invention, the pressure override can be reduced even if the flow rate increases.

It is a vertical sectional view of the relief valve in one embodiment. It is the schematic of the damper to which the relief valve of one Embodiment is applied. (A) is a front view of the valve body of the relief valve in one embodiment. (B) is a side sectional view of the valve body of the relief valve according to the embodiment. (C) is a bottom view of the valve body of the relief valve in one embodiment. (A) is a front view of the valve body of the relief valve in the first modification of the embodiment. (B) is a side sectional view of the valve body of the relief valve in the first modification of the embodiment. (C) is a bottom view of the valve body of the relief valve in the first modification of the embodiment. It is a figure which showed the pressure flow rate characteristic of the relief valve in one Embodiment. It is a figure which showed the flow of the liquid in the relief valve in one Embodiment. It is a figure which showed the damping force characteristic of the damper to which the relief valve of one Embodiment was applied. (A) is a front view of the valve body of the relief valve in the second modification of one embodiment. (B) is a side sectional view of the valve body of the relief valve in the second modification of the embodiment. (C) is the bottom view of the valve body of the relief valve in the second modification of one embodiment. (A) is a front view of the valve body of the relief valve in the third modification of the embodiment. (B) is a side sectional view of the valve body of the relief valve in the third modification of the embodiment. (C) is a bottom view of the valve body of the relief valve in the third modification of the embodiment. It is a figure which showed the damping force characteristic of a damper using a conventional relief valve. It is a figure which showed the flow of the liquid in the conventional relief valve.

Hereinafter, the relief valve V of the present invention will be described with reference to the drawings. As shown in FIG. 1, the relief valve V in one embodiment has a tubular housing 1 having an annular valve seat 2 inside and a valve that is movably housed in the housing 1 and is detached and seated on the annular valve seat 2. A body 3 and a coil spring 4 as a spring for urging the valve body 3 toward the annular valve seat 2 are provided.

The relief valve V is used, for example, by being provided in the middle of the passages 20a and 20b communicating the extension side chamber R1 and the compression side chamber R2 partitioned inside the damper D as shown in FIG. The damper D includes a cylinder 21, a piston 22 slidably inserted into the cylinder 21, and a piston 22 for partitioning an extension side chamber R1 and a compression side chamber R2 in which a liquid such as hydraulic oil is filled in the cylinder 21, and the cylinder 21. It is configured to include a piston rod 23 that is movably inserted inside and connected to the piston 22, and in this case, the damper D is a double-rod type damper. Of course, it may be a single rod type damper.

Further, the piston 22 is provided with passages 20a and 20b, and one relief valve V is installed in the middle of the passages 20a and 20b in a staggered direction. Further, the passages 20a and 20b are provided with a damping valve O parallel to the relief valve V. Then, when the damper D is extended and the piston 22 moves to the left in FIG. 2, the pressure in the extension chamber R1 on the left in FIG. 2 rises, and the pressure reaches the relief pressure of the relief valve V. Then, the relief valve V installed in the middle of the passage 20a opens and releases the liquid in the extension side chamber R1 to the compression side chamber R2 on the right side in the figure while giving resistance to the flow of the liquid and exerting the extension side damping force. .. The relief valve V installed in the middle of the passage 20b remains closed under the pressure of the extension side chamber R1 to shut off the passage 20b. On the contrary, when the damper D contracts and the piston 22 moves to the right in FIG. 2, the pressure in the compression side chamber R2 on the right in FIG. 2 rises, and the pressure reaches the relief pressure of the relief valve V. Then, the relief valve V installed in the middle of the passage 20b opens and releases the liquid in the compression side chamber R2 to the extension side chamber R1 on the left side in the drawing while giving resistance to the flow of the liquid and exerting a damping force. The relief valve V installed in the middle of the passage 20a receives the pressure of the compression side chamber R2 and remains closed to shut off the passage 20a.

In this way, the relief valve V acts as a damping valve that exerts a damping force on the damper D when vibration is input to the damper D. The configuration of the damper D is not limited to the configuration described above. For example, the damper D is a single rod type and has a reservoir tank in addition to the extension side chamber R1 and the compression side chamber R2, and these are communicated in a passage in a string. When the damper D is a uniflow damper that circulates the liquid in the order of the reservoir R, the compression side chamber R2, the extension side chamber R1 and the reservoir tank when the damper D expands and contracts, the relief valve V communicates the extension side chamber R1 and the reservoir tank. It may be installed so as to give resistance when the liquid flows from the extension side chamber R1 toward the reservoir tank in the passage. Further, when the damper D also has a reservoir tank in addition to the extension side chamber R1 and the compression side chamber R2, in the middle of the passage connecting the reservoir tank and the compression side chamber R2 in addition to the passage provided in the piston. Also, a relief valve V may be provided. In any case, the relief valve V may be installed so that the damper D can exert a damping force. Further, the relief valve V can be used not only for the damper D but also for an actuator as well as a hydraulic device using a relief valve.

Going back, each part of the relief valve V will be described in detail below. The housing 1 has a tubular shape, the inner circumference of the tip at the lower end in FIG. 1 is reduced in diameter, and the housing 1 is provided with a small diameter portion 1a and a large diameter portion 1b having an inner diameter larger than that of the small diameter portion 1a. There is. The housing 1 includes an annular valve seat 2 formed by a step portion formed at the boundary between the small diameter portion 1a and the large diameter portion 1b. Further, a screw portion 1c is provided on the inner circumference of the rear end, which is the upper end in FIG. 1 of the housing 1, and a bottomed tubular nut 15 having a screw portion on the outer circumference is screwed to the screw portion 1c. Has been done.

Further, a plurality of through holes 1d that are opened from the side and lead to the inside are provided on the rear end side of the housing 1 with respect to the annular valve seat 2. Therefore, when the relief valve V is provided on the piston 22, the opening at the tip of the housing 1 is made to face one of the extension side chamber R1 and the compression side chamber R2 of the damper D, and the through hole 1d is provided on the piston 22 via a port (not shown). It suffices to communicate with the other of the extension side chamber R1 and the compression side chamber R2.

The valve body 3 is housed in the housing 1 so as to be movable in the axial direction, and as shown in FIGS. 1 and 3, the cylindrical sliding contact shaft 3a sliding on the inner circumference of the small diameter portion 1a of the housing 1 and sliding. A disc-shaped seating portion 3b that connects to the rear end of the tangent shaft 3a, which is the upper end in FIG. 1, and is detached and seated on the annular valve seat 2, and the sliding tangent shaft 3a from the tip to the rear end, which is the lower end of FIG. The main slit 3c, which is formed and opens to the side of the sliding contact shaft 3a, and the sliding contact shaft which opens from a position on the side of the sliding contact shaft 3a and shifted to the tip side from the rear end of the main slit 3c. It is provided with a sub flow path 3d leading to the tip of 3a. Since the sliding contact shaft 3a is in sliding contact with the inner circumference of the small diameter portion 1a of the valve body 3, the valve body 3 can be moved in the housing 1 in the axial direction without axial deviation by using the sliding contact shaft 3a as a guide.

Further, the valve body 3 is provided with a columnar body portion 3e provided at the rear end of the seating portion 3b and protruding in the axial direction, and the outer circumference of the tip of the body portion 3e is enlarged in diameter so that the coil spring 4 is fitted. It is provided with a guide portion 3f having an outer diameter smaller than that of the seating portion 3b.

As shown in FIG. 3, the main slit 3c is formed so as to open from the tip of the sliding contact shaft 3a toward the rear end and penetrates the sliding contact shaft 3a in the radial direction, and the sliding contact shaft 3a is laterally penetrated. When viewed, the rear end shape is semi-circular, and the sliding contact shaft 3a is cut out in a U shape in the radial direction from the side.

As shown in FIG. 3, the sub-flow path 3d opens on the side of the sliding contact shaft 3a, on the tip side of the main slit 3c, and on the side of the sliding contact shaft 3a of the main slit 3c. It is provided so as to widen the circumferential width of the main slit 3c through the side opening O. Specifically, as shown in FIG. 3, the sub-flow path 3d is formed by notches N and N that communicate with each of the two lateral openings O of the main slit 3c of the sliding contact shaft 3a. , The side portion of the sliding contact shaft 3a is cut out from the side in a direction orthogonal to the direction from the front end to the rear end of the main slit 3c to form a rounded corner.

Then, when the seating portion 3b is seated on the annular valve seat 2, the relief valve V is closed and the space inside the large diameter portion 1b of the housing 1 is cut off from the main slit 3c to cut off the communication with the housing 1. Block the inside. On the other hand, the valve body 3 moves upward in FIG. 1 with respect to the housing 1 from the state shown in FIG. 1, the seating portion 3b is separated from the annular valve seat 2, and the main slit 3c is radially in the large diameter portion 1b. When facing each other, the relief valve V is opened and the inside of the housing 1 is opened so that the space inside the large diameter portion 1b and the main slit 3c are communicated with each other. Then, the area where the main slit 3c faces the large diameter portion 1b increases according to the amount of retreat of the valve body 3 from the annular valve seat 2, and the valve opening area increases. Further, as the valve body 3 retreats from the annular valve seat 2, the sub flow path 3d also faces the large diameter portion 1b in the radial direction, and the sub flow path 3d in addition to the main slit 3c has a large diameter portion. It communicates with the space inside 1b. Therefore, the flow path area of the relief valve V is the area obtained by adding the area of the sub flow path 3d facing the large diameter portion 1b to the flow path area of the main slit 3c. In this way, the sub-flow path 3d adds a flow path to the flow path of the main slit 3c in the circumferential direction of the sliding contact shaft 3a. In the embodiment shown in FIG. 3, the sub flow path 3d communicates with the tip end side of the sliding contact shaft 3a through the main slit 3c, and partially with respect to the total length of the sliding contact shaft 3a in the axial direction. Since it is provided, the strength of the tip side of the sliding contact shaft 3a is secured, but as shown in FIG. 4, it may be formed so as to be connected to the tip of the sliding contact shaft 3a.

Further, a spring seat 10 is housed in the housing 1 in addition to the valve body 3, and the spring seat 10 is provided at the columnar spring fitting portion 10a and the rear end of the spring fitting portion 10a. It is provided with a flange-shaped spring receiving portion 10b that is seated on the bottom of the nut 15. A coil spring 4 is interposed between the spring receiving portion 10b and the rear end surface of the seating portion 3b of the valve body 3 in a compressed state. Therefore, the valve body 3 is urged by the urging force generated by the coil spring 4 and pressed toward the annular valve seat 2. The urging force of the coil spring 4 can be adjusted by changing the axial position of the nut 15 with respect to the housing 1.

The spring seat 10 and the nut 15 may be made into one part, but since the spring seat 10 and the nut 15 are separate parts, there is play in the radial direction of the spring seat 10 with respect to the nut 15. By holding the spring seat 10, the spring seat 10 can be easily fitted to the valve body 3, and the ease of assembly of the relief valve V is improved without requiring a high degree of dimensional control.

The relief valve V is closed until the force that pushes the valve body 3 upward in FIG. 1 due to the pressure acting on the valve body 3 from the upstream side overcomes the urging force that pushes the valve body 3 of the coil spring 4 downward in FIG. When the valve state is maintained and the force overcomes the urging force of the coil spring 4, the valve body 3 compresses the coil spring 4 and retracts from the annular valve seat 2 to open the valve. That is, in the relief valve V, the relief pressure (valve opening pressure) can be adjusted by adjusting the urging force generated by the coil spring 4 in the closed state. When the relief valve V is opened, the liquid that has pushed the valve body 3 away and passed through the main slit 3c escapes into the large diameter portion 1b of the housing 1 and out of the housing 1 through the through hole 1d.

The greater the pressure acting on the valve body 3, the greater the force pushing up the valve body 3 in FIG. 1, so that the amount of retreat of the valve body 3 away from the annular valve seat 2 increases, but the annular valve seat When the amount of retreat from 2 becomes a predetermined amount of retreat, not only the main slit 3c but also the sub flow path 3d faces the large diameter portion 1b, and the flow path in the relief valve increases in the circumferential direction of the sliding contact shaft 3a.

The lower end of the coil spring 4 in FIG. 1 is fitted to the outer circumference of the guide portion 3f of the valve body 3, and the upper end in FIG. 1 which is the other end is the outer circumference of the spring fitting portion 10b of the spring seat 10. Even if the coil spring 4 is bent in the radial direction, it is designed so as not to interfere with the outer circumference of the body portion 3e of the valve body 3 other than the guide portion 3f.

In the relief valve V configured in this way, all the constituent members are integrated into the housing 1 to form a cartridge as described above. For example, as described above, the passages 20a and 20b provided in the piston 22 of the damper D are provided. Etc. are inserted and fixed for use. Specifically, the piston 22 is provided with a hole and a port leading to the through hole 1d to form passages 20a and 20b, and the relief valve V cartridgeized as described above is formed in the hole forming the passages 20a and 20b. Then, the relief valve V may be fixed to the passages 20a and 20b by screwing an annular nut into the hole.

Next, the operation of the relief valve V will be described by taking the case where it is installed in the passage 20a of the damper D as an example. As described above, the relief valve V is used in combination with the damping valve O. When an external force directed to the left in FIG. 2 acts on the piston 22, the pressure in the extension side chamber R1 on the left side in the figure rises, but when the pressure in the extension side chamber R1 does not reach the valve opening pressure of the relief valve V, the valve is valved. The body 3 remains seated on the annular valve seat 2, and the liquid passes only through the damping valve O and moves from the extension side chamber R1 to the compression side chamber R2. Therefore, as shown by line X in FIG. 5, the pressure flow rate characteristic of the damping valve O has a characteristic of having a large inclination, and when the piston speed is in the low speed range, the relief valve V does not open and attenuates. The characteristics of valve O only appear.

When the pressure in the extension side chamber R1 becomes higher than the valve opening pressure of the relief valve V, the valve body 3 receives the pressure and retracts from the annular valve seat 2 to open the relief valve V, and the liquid is the main slit 3c. It passes through the large diameter portion 1b and the through hole 1d of the housing 1 and moves to the compression side chamber R2. The amount of retreat of the valve body 3 from the annular valve seat 2 increases as the pressure in the extension side chamber R1 rises, but when the piston speed is in the medium speed range, only the main slit 3c has a large diameter portion. The sub flow path 3d is not opened only by facing 1b in the radial direction. Therefore, when the piston speed of the damper D is in the medium speed range and the flow rate passing through the relief valve V is small, the flow path area of the relief valve V is small and the resistance is large.

On the other hand, when the piston speed reaches a high speed range, the amount of retreat from the annular valve seat 2 of the valve body 3 becomes large, and the sub flow path 3d also faces the large diameter portion 1b in the radial direction after the opening of the main slit 3c. Become. When the sub flow path 3d is opened facing the large diameter portion 1b, the liquid passes through not only the main slit 3c but also the sub flow path 3d. Then, as shown in FIG. 6, the sub-flow path 3d circulates the flow path area of the relief valve V by adding a flow path in the circumferential direction of the sliding contact shaft 3a in addition to the flow path formed by the main slit 3c. It expands in the direction and disperses the flow of liquid in the circumferential direction. As described above, in the relief valve V of the present embodiment, the flow of the liquid is dispersed in the circumferential direction of the sliding contact shaft 3a as compared with the relief valve having only the main slit. Therefore, the relief valve V of the present embodiment can suppress the flow of the liquid from concentrating on a very small part in the circumferential direction of the sliding contact shaft 3a and disperse the flow. The maximum value in the flow rate distribution of is smaller than that of the conventional relief valve. From the above, even if the flow of the liquid passing through the main slit 3c and the sub-flow path 3d and toward the inside of the large diameter portion 1b of the housing 1 is bent in the housing 1, the flow rate is reduced and the resistance given to the flow of the liquid is reduced. Also becomes smaller. As a result, the pressure flow rate characteristic of the relief valve V when the flow rate increases is the characteristic of the conventional relief valve (in FIG. 5) because the sub-flow path 3d is opened as shown by the line Y in FIG. Compared with the line Z), the pressure override in the high speed range is reduced, and the increase in pressure loss becomes extremely small as the flow rate increases. Therefore, as shown in FIG. 7, the damping force characteristics of the damper D equipped with the relief valve V show the characteristics of the damping valve O when the piston speed is in the low speed range, and the damping coefficient is large, but the piston speed is high. When the valve is in the medium speed range, the relief valve V opens and the damping coefficient becomes small. When the piston speed is in the high speed range, the increase in the damping coefficient is suppressed and the damping force increases with respect to the increase in the piston speed. The characteristic is that the increase is negligible.

As described above, the relief valve V of the present embodiment has a tubular housing 1 having an annular valve seat 2 inside and a valve body that is movably housed in the housing 1 and is detached and seated on the annular valve seat 2. 3 and a coil spring (spring) 4 for urging the valve body 3 toward the annular valve seat 2 are provided, and the valve body 3 has a sliding contact shaft 3a that is in sliding contact with the inner circumference of the housing 1 and a sliding contact shaft 3a. A disc-shaped seating portion 3b that is connected to the rear end and is detached and seated on the annular valve seat 2, and a main slit that is formed from the tip of the sliding contact shaft 3a toward the rear end and opens to the side of the sliding contact shaft 3a. 3c and the flow path formed by the main slit 3c, which is on the side of the sliding contact shaft 3a and is open from the tip side of the rear end of the main slit 3c and leads to the tip of the sliding contact shaft 3a, in the circumferential direction. It includes a sub-flow path 3d to which a flow path is added.

According to the relief valve V configured in this way, as described above, when the valve body 3 retreats from the annular valve seat 2, the sub flow path 3d is opened behind the opening of the main slit 3c, and the sub flow path 3d is opened. The path 3d adds a flow path to the flow path of the main slit 3c in the circumferential direction of the sliding contact shaft 3a to disperse the flow of the liquid in the sub flow path 3d. Therefore, according to the relief valve V of the present embodiment, the pressure override can be reduced even if the flow rate increases. Further, since the sub flow path 3d is not opened when the flow rate is low, it does not affect the characteristics of the relief valve V when the flow rate is low. Therefore, in the relief valve V shown in FIG. 3, the pressure override when the flow rate is large can be reduced without affecting the pressure flow rate characteristic when the flow rate is small.

Further, the main slit 3c in the relief valve V of the present embodiment is formed so as to penetrate the sliding contact shaft 3a in the radial direction, and the sub flow path 3d opens when the seating portion 3b retracts from the annular valve seat 2. The flow rate of the main slit 3c is dispersed, and the flow of the liquid is diffused in the circumferential direction of the sliding contact shaft 3a. When the sub-flow path 3d disperses the liquid flow in the circumferential direction in this way, the flow rate distribution passing between the housing 1 and the seating portion 3b of the valve body 3 is dispersed in the circumferential direction, so that the liquid becomes more liquid. The resistance due to the flow being bent by the housing 1 is reduced, and the pressure override described above can be further reduced.

In the relief valve V of the present embodiment, the main slit 3c penetrates the sliding contact shaft 3a in the radial direction and is formed from the tip end to the rear end of the sliding contact shaft 3a, and the sub flow path 3d is on the side of the sliding contact shaft 3a. It is formed so as to open from the side and communicate with the side opening O of the main slit 3c. According to the relief valve V configured in this way, since the sub flow path 3d is directly communicated with the side opening O of the main slit 3c, the liquid that has passed through the narrow main slit 3c is the sub flow path 3d. As it opens, it penetrates into the sub-flow path 3d that is wide in the circumferential direction, and the liquid flow is efficiently diffused in the circumferential direction of the sliding contact shaft 3a. According to the relief valve V configured in this way, the liquid flow can be efficiently diffused in the circumferential direction by the sub-flow path 3d, so that the pressure override of the relief valve V can be effectively reduced. Further, since the guide area of the sliding shaft 3a is secured, it is possible to achieve both after securing the opening area and suppressing the shaft shake of the valve body 3.

As for the specific configuration of the sub-flow path 3d, in addition to providing the notch N on the sliding contact shaft 3a, a lateral hole 30 communicating with the main slit 3c is provided as shown in FIG. As shown in FIG. 9, the sub-slit 31 is formed so as to penetrate the sliding contact shaft 3a in the radial direction and to be formed in a direction orthogonal to the main slit 3c from the tip end to the rear end of the sliding contact shaft 3a. It may be provided and this may be used as a sub-channel. In this way, even if the sub-flow path is formed by the lateral hole 30 or the sub-slit 31, when the valve body 3 retracts from the annular valve seat 2 and the sub-flow path is opened, the sub-flow flows into the flow path of the main slit 3c. A flow path can be added to disperse the flow of liquid. If the flow of the liquid is dispersed, the flow rate distribution passing between the housing 1 and the seating portion 3b of the valve body 3 can be dispersed, so that the pressure override of the relief valve V when the flow rate becomes large can be reduced.

Although the preferred embodiments of the present invention have been described in detail above, modifications, modifications, and changes can be made without departing from the scope of the claims.

1 ... housing, 2 ... annular valve seat, 3 ... valve body, 3a ... sliding contact shaft, 3b ... seating part, 3c ... main slit, 3d ... sub flow path 4, 4 ... Coil spring (spring), 30 ... Horizontal hole (sub flow path), 31 ... Sub slit (sub flow path), O ... Side opening, V ... Relief valve

In order to solve the above problems, the relief valve of the present invention includes a tubular housing having an annular valve seat inside, a valve body that is movably housed in the housing and is detached and seated on the annular valve seat, and a valve body. The valve body is provided with a sliding contact shaft that is in sliding contact with the inner circumference of the housing and a circle that is connected to the rear end of the sliding contact shaft and is detached and seated on the annular valve seat. A plate-shaped seating portion, a main slit formed from the tip to the rear end of the sliding contact shaft and opening to the side of the sliding contact shaft, and a side of the sliding contact shaft from the rear end of the main slit. Also has a sub-flow path that opens from the tip side and adds a flow path in the circumferential direction to the flow path formed by the main slit leading to the tip of the sliding contact shaft, and the sliding contact shaft is the seating portion. It is located upstream of . According to the relief valve configured in this way, as the valve body retracts from the annular valve seat, the sub flow path is opened later than the opening of the main slit, and the sub flow path is in sliding contact with the flow path of the main slit. A flow path can be added in the circumferential direction of the shaft to disperse the flow of liquid in the sub-flow path.

Also, the main slits of the relief valve, is formed to penetrate the sliding axis in the radial direction, the sliding contact with the sub-channel disperses the flow rate of the main slit the seat is opened to retract from the annular valve seat The flow of liquid may be diffused in the circumferential direction of the shaft. According to the relief valve configured in this way, the sub-flow path increases the area of the liquid outlet to facilitate the diffusion of the liquid flow, and the flow rate distribution passing between the housing and the seating portion of the valve body is distributed. Since it is dispersed in the circumferential direction, the resistance due to the liquid flow being bent by the housing is reduced, and the pressure override can be further reduced.

Further, the piston 22 is provided with passages 20a and 20b, and one relief valve V is installed in the middle of the passages 20a and 20b in a staggered direction. Further, the passages 20a and 20b are provided with a damping valve DV parallel to the relief valve V. Then, when the damper D is extended and the piston 22 moves to the left in FIG. 2, the pressure in the extension chamber R1 on the left in FIG. 2 rises, and the pressure reaches the relief pressure of the relief valve V. Then, the relief valve V installed in the middle of the passage 20a opens and releases the liquid in the extension side chamber R1 to the compression side chamber R2 on the right side in the figure while giving resistance to the flow of the liquid and exerting the extension side damping force. .. The relief valve V installed in the middle of the passage 20b remains closed under the pressure of the extension side chamber R1 to shut off the passage 20b. On the contrary, when the damper D contracts and the piston 22 moves to the right in FIG. 2, the pressure in the compression side chamber R2 on the right in FIG. 2 rises, and the pressure reaches the relief pressure of the relief valve V. Then, the relief valve V installed in the middle of the passage 20b opens and releases the liquid in the compression side chamber R2 to the extension side chamber R1 on the left side in the drawing while giving resistance to the flow of the liquid and exerting a damping force. The relief valve V installed in the middle of the passage 20a receives the pressure of the compression side chamber R2 and remains closed to shut off the passage 20a.

Next, the operation of the relief valve V will be described by taking the case where it is installed in the passage 20a of the damper D as an example. As described above, the relief valve V is used in combination with the damping valve DV . When an external force directed to the left in FIG. 2 acts on the piston 22, the pressure in the extension side chamber R1 on the left side in the figure rises, but when the pressure in the extension side chamber R1 does not reach the valve opening pressure of the relief valve V, the valve is valved. The body 3 remains seated on the annular valve seat 2, and the liquid passes only through the damping valve DV and moves from the extension side chamber R1 to the compression side chamber R2. Therefore, as shown by line X in FIG. 5, the pressure flow rate characteristic of the damping valve DV has a characteristic of having a large inclination, and when the piston speed is in the low speed range, the relief valve V does not open and attenuates. The characteristics of only the valve DV appear.

On the other hand, when the piston speed reaches a high speed range, the amount of retreat from the annular valve seat 2 of the valve body 3 becomes large, and the sub flow path 3d also faces the large diameter portion 1b in the radial direction after the opening of the main slit 3c. Become. When the sub flow path 3d is opened facing the large diameter portion 1b, the liquid passes through not only the main slit 3c but also the sub flow path 3d. Then, as shown in FIG. 6, the sub-flow path 3d circulates the flow path area of the relief valve V by adding a flow path in the circumferential direction of the sliding contact shaft 3a in addition to the flow path formed by the main slit 3c. It expands in the direction and disperses the flow of liquid in the circumferential direction. As described above, in the relief valve V of the present embodiment, the flow of the liquid is dispersed in the circumferential direction of the sliding contact shaft 3a as compared with the relief valve having only the main slit. Therefore, the relief valve V of the present embodiment can suppress the flow of the liquid from concentrating on a very small part in the circumferential direction of the sliding contact shaft 3a and disperse the flow. The maximum value in the flow rate distribution of is smaller than that of the conventional relief valve. From the above, even if the flow of liquid passing through the main slit 3c and the sub flow path 3d and toward the inside of the large diameter portion 1b of the housing 1 is bent in the housing 1, the flow rate is reduced and the resistance given to the flow of liquid Also becomes smaller. As a result, the pressure flow rate characteristic of the relief valve V when the flow rate increases is the characteristic of the conventional relief valve (in FIG. 5) because the sub-flow path 3d is opened as shown by the line Y in FIG. Compared with the line Z), the pressure override in the high speed range is reduced, and the increase in pressure loss becomes extremely small as the flow rate increases. Therefore, as shown in FIG. 7, the damping force characteristic of the damper D equipped with the relief valve V shows the characteristic due to the damping valve DV when the piston speed is in the low speed range, and the damping coefficient is large, but the piston speed is high. When it is in the medium speed range, the relief valve V opens and the damping coefficient becomes small, and when the piston speed is in the high speed range, the increase in the damping coefficient is suppressed and the damping force increases with respect to the increase in the piston speed. The characteristic is that the increase is negligible.

Claims (5)

A tubular housing with an annular valve seat inside,
A valve body that is movably housed in the housing and takes off and seats on the annular valve seat.
A spring for urging the valve body toward the annular valve seat is provided.
The valve body includes a sliding contact shaft that is in sliding contact with the inner circumference of the housing, a disc-shaped seating portion that is connected to the rear end of the sliding contact shaft and is detached and seated on the annular valve seat, and the tip of the sliding contact shaft. A main slit that is formed from the rear end to the rear end and opens to the side of the sliding contact shaft, and the sliding that is lateral to the sliding contact shaft and opens from the tip side of the rear end of the main slit. A relief valve characterized by having a sub-flow path that adds a flow path in the circumferential direction to the flow path formed by the main slit leading to the tip of the tangent shaft. The main slit is formed so as to penetrate the sliding contact shaft in the radial direction.
The claim is characterized in that when the seating portion retracts from the annular valve seat and opens, the sub-flow path disperses the flow rate of the main slit and diffuses the flow of liquid in the circumferential direction of the sliding contact shaft. Item 1. The relief valve according to item 1. The main slit is formed so as to penetrate the sliding contact shaft in the radial direction and from the tip end of the sliding contact shaft toward the rear end.
The first or second aspect of the present invention, wherein the sub-flow path opens from the side of the sliding contact shaft and communicates with a lateral opening of the main slit which opens to the side of the sliding contact shaft. Relief valve. The main slit is formed so as to penetrate the sliding contact shaft in the radial direction and from the tip end of the sliding contact shaft toward the rear end.
Claim 1 is characterized in that the sub-flow path penetrates the sliding contact shaft in the radial direction and is formed in a direction orthogonal to the main slit from the tip end to the rear end of the sliding contact shaft. Relief valve described in. The main slit is formed so as to penetrate the sliding contact shaft in the radial direction and from the tip end of the sliding contact shaft toward the rear end.
The relief valve according to claim 1, wherein the sub-flow path is a lateral hole that opens from the side of the sliding contact shaft and communicates with the main slit.

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